Yates Heads on the street?

[RRD]

OK, fess up. Who's running a set of Yates on the street? I'm having my "big" smallblock assembled (4.125 bore x 4" stroke); and I'm goiing to use a set of "small port" Yates with a port matched single plane and 850 Holley. Who has some cam advice to make this thing anything but a full time job to run on the street? It will only see track use about 10-20 % of the time, and I don't want it to be so miserable to drive that it's a hanger queen. Who has some cam specs in a similar situation that they were happy with?

Thanks,
RD

[jmarsey]

RD,

I would recommend you get some expert advice with this combination. Keith Kraft would be my first phone call. 870-246-7460

John

[Jack21]

Thoughts,

You've got the cubes to support the airflow for Yates, Blue Thunder, etc. Cleveland style heads, but for mostly street use don't build an engine that only starts working after 3000RPM.

1) Substitute a 750DP Demon for the 850 Holley. You'll like the responsiveness better.

2) Use a dual plane rather than a single plane intake.

3) Talk to Crane Cams about a hydraulic roller cam, but keep intake duration in the 224 deg @.050. rane likes dual patter cams and might go 234 deg exh @.050. This should get you in the ballpark for a good street motor that should wax any FE. Some of the smaller specialty shops mentioned here should have more optimized recommendation for this motor and intended use.

[coyled]

RD, Yes, you can run the yates on the street. For these heads to work well you need plenty of cam timing and a 3.50 or lower rear end. I would run a single plane. Just remember, a yates head is an all out no compromise race head. Scott

[hound dog]

RD,
With a 427 small block you will need heads that have comparable airflow to big block heads. That leaves you with the Yates heads, Victors, or AFR 225's and these are just barely enough. The Edelbrock and AFR heads use mostly off the shelf components but you are rather limited with the Yates heads. I believe that you are limited to using their single plane intake and a dual plane is not available. I'm running Victor junior heads and intake and I don't have any problems with hesitation, loading or anything else. So don't be afraid to run a single plane if that is what you want. I'm also using a Lunati 51012 hydraulic roller cam which comes on at 2800 rpms. This setup is about max. for the street. I would recommend it but realize that this is about the upper limit for street management. Remember that you are only under 3000 rpms for about half a second in the Stoplight Gran Prix.
h dog

[RRD]

First, thanks to all for the input. I appreciate it. Today I spoke with Bennet, Craft, Comp and Mckeown Motorsport. Bennet advocated the biggest cam with the largest centerline; like mid 240"s at 112-114 degrees. Mar Mckeown took the most time, was the most analyitical and, at least to me, seemed for this task to be the guy I'm going with. Here's the deal, minimum low to mid 230's at .o50, 109-110 degrees. Maximum mid 140's; lots more power, but start to pay some driveability price... Hydraulic roller .575 to .600 lift. Not a valve spring maint hog at all, he says probably won't have to touch them for several years unless starting to tread much in the 6500 -7400 rpm area. No thanks, don't need it. Probably will be hard to keep under 550 hp anyway. What's 1900 divided by 550?? Certainly low enough for me... He told me that Yates himself was originally a diesel mechanic, and that Yates still runs his own team's engines with a longer stroke and larger dished piston than others; says it's all about building cylinder pressure, and they do not like over 110 degree centerline at all. Mark says he has a lot of dyno time, street motors to Grand National and Pro Stock to go by. Good enough for me. For anyone interested:

Mark Mckeown
Mckeown Motorsport Engineering
Nanjemoy
MD
20662

301-246-9225

...Good Guy (not that the others are not...)

[Tony Radford]

RRD, if you're going to spend 80-90% of your time on the street, do you really want to compromise streetability? I know a number of folks who crossed the threshold and regret it. Our local engine builder (Southern Automotive) does a great job of managing performance VS street manners. I'm running Twisted Wedge heads and Vic. Jr. intake, but each has been heavily ported and matched right through to the header flanges. My tire budget will certainly be affected. Light weight pistons, solid flat tappet cam/lifters, Demon performance carb and aluminum flywheel means instantaneous throttle response. Just something to consider!

[750hp]

FWIW - I've never seen a Cobra with too much camshaft. All of the streetability issues in normal (ie: heavy) street driven cars are not such a big deal with a Cobra. There are a couple of guys using Yates heads out here without a problem. They're in the 375 - 380 cube range, and they're running MUCH larger camshafts than what you've described. The light weight, combined with 3.5 or steeper rear gears, meant that any loss of low-rpm torque was never noticed. The overdrive 5th gear meant that cruising rpm is still fine with the steeper rear end gears...

While I do like the lower maintenance of hyd rollers, I wouldn't be concerned about wearing out valve springs with a large camshaft. There are still some pretty radical hydro roller profiles available. My solid roller camshaft was designed for pretty high spring pressure (240lb !), but every time I've had a rocker cover off the motor, I've checked the springs. They haven't lost any pressure since they were installed over 2 years ago. They've been through 2 complete engine dyno sessions, and I haven't been exactly kind to them while the engine's been in my car

[scottj]

I’m very happy with my cam. It is basically the same cam that's in my 434ci race engines: Solid roller, 264/272@.050, .680 lift, 106* lobe separation for street, 108* lobe separation for race.

430 inch small blocks can use a bit more cam without losing drivability, especially if the port size is kept small to maintain low rpm velocity. With small ports, mine will cruise at 2200rpm, idle at 1200rpm, and run out of breath at 7100 rpm. Where as the same cam will turn 8000rpm in my race engine with big heads. With the small-port street combination, low rpm torque is excessive, even with 13” RR slicks.

Get it carbed correctly and it wont be bad to drive on the street. This combination needs a custom calibrated carb from a good carb builder, not for power but for drivability. An off the shelf carb, whether a Holley, Demon, or whatever, usually will give up some drivability with this type of combination. Street calibrations are the hardest to get right, I think DaVinci does Craft’s and I’m very happy with my Stealths.

Scott

[coyled]

Scottj, my cam is 265 duration and .670 lift, .690 lift on 108 lobe centers. 12 to 1's with yates heads, 358ci. So far , good luck with the valve springs and when they are adjusted every track event, they are not off by much. I run a 3.89 gear and fuel injection. It is very streetable. Funny that are cam timing is so close. Scott

[Bart Carter]

Coyled,

What octane can you run?

[RRD]

Coyled,
My last 408 had your cam specs spot on. It was in an early Mustang chassis, and despite all the nylon straps and big guys sitting on the rear deck, once the dyno hit 425 at the rear wheels, the rest was smoke; just not enough tire section to get the job done. I was using MUCH modified N351 "Yates Style" heads that had very generous ports. Frankly, huge. If the port size was any smaller, and I could have enjoyed a bit more velocity at low RPMs, it probably would not have been a full time job to manage it on the street. Yes, foot to the wood, it would deposit the rear tire until I ran out of guts/stupidity (take your choice). That particular head only began to work at about 3800-4000, which is above where I want to go now. Mckoewn is saying my last combination was not well matched; it was not the cam at fault. I guess to have the Yates and not give it the cam specs that it was designed to accompany is a waste of the heads and intake. You guys are right also, between the displacement and weight issues, um, we're not moving a city bus from stoplight starts here, are we? Anyway, thanks for the input, I am going with Mckoewn, who, BTW has his own profiles ground on billet cores, not cast iron. Even with roller rockers, the amount of spring pressure we're all having to run would seem to wear out an iron core a bit faster.

[Bart Carter]

I chose heads to give more power at higher RPM.

This gives me much more control/driveability for the street at low RPM and much more power on the track at high RPM.

[scottj]

Coyled- I wouldn’t be surprised by the cam similarities if we were comparing all-out race engines. But, I must admit I was more than a little surprised by ProPower’s choice of cam for my street engine. When I told them my plans for the engine I said I wanted a pump gas street engine that wont embarrass me at R&G (my driving skills would provide all the embarrassment I can handle ).

I’ve got 2000 miles and so far no lifter failures or weak valve springs. I check lash frequently and keep a chart on changes to each valve. I haven’t had to adjust more than .002-.003 total so far.

RRD- Your right no cast cores or small base circles; billet only. The only thing that really concerns me is the lifters.

Scott

[coyled]

Scottj, I have over 6000 miles on mine with no valve spring or lifter failures so far, knock on wood. Bart, what heads are you running? Gordon sais your cobra runs and handles very well. I am thinking about going out to AMP November 22 and 23. Any interest? Its an AZRA event but it would be interesting to run with other cobra's. Scott

[Bart Carter]

Originally posted by coyled Bart, what heads are you running? Gordon says your cobra runs and handles very well. I am thinking about going out to AMP November 22 and 23. Any interest? Its an AZRA event but it would be interesting to run with other cobra's. Scott

I have the Brodix Neal 200's. I am VERY happy with the engine.

AMP sounds tempting. I'll have to see what my schedule allows after this week.

I would love to run the track with you. You can show me the correct line. My car is still way faster than I am. I ususally run NASA HPDE 4. What would I be running in AZRA?

[coyled]

I have not run there so I don't know the line. My car is also much faster than I can drive it. I ran in hpde4 the last time I ran with nasa. I have run with azra once and like nasa, I think I would be in the fastest non race group. I have a few brake issues to resolve but I would like to run on saturday or sunday. I run pump gas on the street and race gas at the track. Have you run AMP?Scott.

[Bart Carter]

Ran AMP the last NASA event. Never seen the track before and it took some to start learning the lines. When I run again, I'll be able to work on some speed through the different turns.

It was mostly a chassis tuning session by Levy Racing. Those guys really know their stuff. They had the suspension close to begin with and then started really fine tuning it. I think it is as good as it gets now, but they are looking to making custom upper/lower A-arms to further enhance the geometry.

I was getting comfortable the last couple of sessions, but there are so many corners that I just didn't take fast enough. I know there was a lot of time to be made up.

I'll have to work a little harder on my schedule to see if I can make it down.